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Appendix II,                              #33

the  Babcock-Wilcox,  and the Herrtsdwf is a coil   boiler with
f>ump circulation.    (Saff. 918, 993,0;^ 1061.)

Plugs (see also p. 755).    Fig. 802 is a section of

one   of   these   as introduced  by the National  Boiler Insurance
Company.     The white-metal should be renewed annually.


JP. 367. Modulus of Resilience,— -The greatest clastic
stress is often called jtrocf stress. Then, from diagram 2, Fig, 326,
we may define resilience as ( half proof load x proof strain,' or


But A

-.  Resilience

and W

(A volume).

The quantity /2~E is termed the modulus oj resiliency and
measures resistance to impact per cubic inch of the bar.

61 .—Compare the resilience per unit volume of two bolts
A arid B, In which for ^ Its length A has a sectional area *8 of the
remaining ft : and B has for & its length a sectional area 'B of the
remaining $j (Hons. Mach. Canst. Exam. i8«9i).

In each case let/"« unit stress on smaller area
and 'Sj « nnlt stress on larger area.
Also let a « larger area, an<l *S a » smaller area,
Then, talcing "bolt A, total resilience